You only have a 24 hour wind for ovulation. The pill may have worked. I don't know, but it may not have worked either. It takes about 2 weeks for implanting to be completed. The ovulation test only tells you when your fertile, and it only a 24 hour window like I said.
There is now way of knowing, plan b is not 100% effective. You are just going to have to wait and see. Even if you aren't pregnant there is no guarantee it's because of the plan b. Very few couples get pregnant the first month they try.